Digital watermarking is a process for modifying physical or electronic media to embed a machine-readable code into the media. The media may be modified such that the embedded code is imperceptible or nearly imperceptible to the user, yet may be detected through an automated detection process. Most commonly, digital watermarking is applied to media signals such as images, audio signals, and video signals. However, it may also be applied to other types of media objects, including documents (e.g., through line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host media signal, and a decoder that detects and reads the embedded watermark from a signal suspected of containing a watermark (a suspect signal). The encoder embeds a watermark by altering the host media signal. The reading component analyzes a suspect signal to detect whether a watermark is present. In applications where the watermark encodes information, the reader extracts this information from the detected watermark.
Several particular watermarking techniques have been developed. The reader is presumed to be familiar with the literature in this field. Particular techniques for embedding and detecting imperceptible watermarks in media signals are detailed in the assignee's co-pending application Ser. No. 09/503,881 (now U.S. Pat. No. 6,614,914) and U.S. Pat. No. 5,862,260, which are hereby incorporated by reference.
The invention relates to watermark encoding and decoding in imaging devices, such as printers and scanners, and imaging device interfaces. One aspect of the invention is a method and system for image watermark decoding in a print process pipeline. The method performs watermark decoding on an image as it is being transferred from one stage of a printing process to another. In particular, in one implementation, a streaming mode watermark decoder operates on sequential portions of the image in a sequential stream passing from one stage of a print process to another. The streaming mode decoder may be incorporated in a printer driver in a computer connected to a printer peripheral or within a printer device.
This type of watermark decoder can be incorporated into a printer driver or printer device for a variety of applications. One application is counterfeit deterrence. Specifically, the decoder can be used to detect a watermark in a high value document (e.g., bank note, check, authentication label, ticket, identity document, etc.) as it is being printed and inhibit the printing process so that printer output is incomplete. Another application is to associate the image being printed with metadata and to render that metadata during the print process. The watermark includes metadata or a reference to metadata in an external database (either within the printer system or in a remote database via a network connection, e.g., on the Internet). Rendering the metadata may include displaying information and/or executing some program or hardware function associated with the image being printed, such as fetching and rendering a related web page referenced via the watermark message.
Another aspect of the invention is a method and system for image watermark encoding in a print process pipeline. The method performs watermark encoding on an image as it is being transferred from one stage of a printing process to another. In particular, in one implementation, a streaming mode watermark encoder operates on sequential portions of the image in a sequential stream passing from one stage to another. This type of encoder can be incorporated into a printer driver or printer device for a variety of applications.
One application is to encode user information as a document is being printed. This user information may be used for counterfeit deterrence by embedding tracer information in the document that will help identify the maker of the counterfeit document. Another application is to associate other forms of metadata about the document as it is being printed by embedding the metadata or a reference to the metadata in a watermark.
Yet another aspect of the invention is a method and system for image watermark decoding in a scanner pipeline. The method performs watermark decoding on an image as it is being transferred from one stage of a scanning process to another. In particular, in one implementation, a streaming mode watermark decoder operates on sequential portions of the image in a sequential stream passing from one stage to another. This type of decoding can be used for a variety of applications, including those mentioned previously for printer drivers and devices. In particular, it can be used to discontinue the unauthorized image scan of a high value document, such as a bank note, identify document, ticket, check, etc. Further, information decoded from the watermark may include metadata or a reference to metadata in an external database. Upon decoding this information, the watermark decoder fetches and renders the metadata.
Yet another aspect of the invention is a method and system for image watermark encoding in a scanner pipeline. The method performs watermark encoding on an image as it is being transferred from one stage of a scanning process to another. In particular, in one implementation, a streaming mode watermark encoder operates on sequential portions of the image in a sequential stream passing from one stage to another. This type of decoding can be used for a variety of applications, including those mentioned previously for printer drivers and devices. One application is to encode user information in an image before it is transmitted to another process or application. For example, in fax machines, the encoder may be used to embed information about the sender or receiver of a fax image in the image before transmitting the image over a telephone connection.
By incorporating watermark functions in imaging devices or their drivers, these functions are inherently available for many software processes or hardware devices that communicate with the imaging devices.
Further features will become apparent with reference to the following detailed description and accompanying drawings.